The invention relates to a cooling channel piston which has a radially circumferential cooling channel located behind a ring field.
A generic cooling channel piston and a method for producing same is known from DE 100 13 395 C1. In this cooling channel piston a piston blank is forged from a steel material, the forging process having the advantage that a material microstructure with especially high strength properties is produced. This is necessary to meet the strength demands placed on cooling channel pistons when used in modern internal combustion engines. These strength demands result, in particular, from the ever-increasing combustion pressures, combustion temperatures and injection pressures of the fuel injected into the cylinder chamber of the internal combustion engine.
After the piston blank has been forged and piston skirts and piston bosses have already been forged integrally therewith, the cooling channel is cut between an upper part and a lower part of the piston by machining in a number of steps. In the process disclosed in DE 100 13 395 C1 it is especially advantageous that the cooling channel is cut in a particular manner, so that the cooling channel extends behind the ring field in the direction of an upper face of the upper part of the cooling channel piston, in order, firstly, to increase the volume of the cooling channel and, secondly, to keep the overall height of the piston as low as possible. In order to implement the function of the cooling channel, namely the circulation of a coolant such as engine oil in the cooling channel, it is also necessary for the cooling channel to be closed by a closing element. Owing to the design of the cooling channel piston of DE 100 13 395 C1, it is possible to close the closing element only in a plane parallel to a plane of the upper face of the piston crown. This means, however, that the gap cut radially between the lower part and the upper part of the cooling channel piston remains and a weakening of the piston in operation in the cylinder chamber of the internal combustion engine results.
It would be desirable to make available a cooling channel piston which is improved with respect to the cooling channel piston of the prior art and which, in particular, meets the necessary strength demands during its operation in the cylinder chamber of the internal combustion engine.